Re: [PATCH 21/21] media: atomisp: csi2-bridge: Set PMC clk-rate for sensors to 19.2 MHz

From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	 Andy Shevchenko <andy@kernel.org>, Kate Hsuan <hpa@redhat.com>,
	Tsuchiya Yuto <kitakar@gmail.com>,
	 Yury Luneff <yury.lunev@gmail.com>,
	Nable <nable.maininbox@googlemail.com>,
	 andrey.i.trufanov@gmail.com,
	Fabio Aiuto <fabioaiuto83@gmail.com>,
	 linux-media@vger.kernel.org, linux-staging@lists.linux.dev
Subject: Re: [PATCH 21/21] media: atomisp: csi2-bridge: Set PMC clk-rate for sensors to 19.2 MHz
Date: Tue, 30 May 2023 00:48:10 +0300	[thread overview]
Message-ID: <CAHp75Ve6rWtkDowBS7z1f=Ot7h8xmXTws8L+Z3eXEfFum2pBcA@mail.gmail.com> (raw)
In-Reply-To: <20230529103741.11904-22-hdegoede@redhat.com>

On Mon, May 29, 2023 at 1:39 PM Hans de Goede <hdegoede@redhat.com> wrote:
>
> The ACPI code takes care of enabling/disabling the PMC clk(s) for
> the sensors as necessary based on the runtime-pm state of the sensor.
>
> But the GMIN code this replaces also set the clk-rate of the PMC clk
> to 19.2 MHz. At least on BYT devices the PMC clks may come up running
> at 25 MHz instead of the expected 19.2 MHz.
>
> Ensure the sensor clk also runs at the expected 19.2 MHz for sensors
> using v4l2-async probing by explicitly setting it to 19.2 MHz when
> enumerating sensors in atomisp_csi2_bridge.c.

...

> +       ret = clk_prepare_enable(clk);
> +       if (!ret)
> +               clk_disable_unprepare(clk);

I'm wondering if _enable / _disable required.

-- 
With Best Regards,
Andy Shevchenko